Laminated product



Patented Sept. 29, 1942 UNITED STATES LAMINATED PRODUCT Adolf Kampfer, Berlin, Germany; vested in th e f Alien Property Custodian No Drawing. Application October 21, 1939, Serial No. 300,657. In Germany April 12, 1935 2 Claims.

The invention of my present application which is a continuation in part of my former application Serial No. 42,357, filed September 26, 1935, relates to an improved laminated glass and the like, containing an intermediate sheet of a highly polymerized acrylic acid ester or vinyl acetate, as hereinafter defined, and more particularly to a means of producing adhesion between such intermediate sheet and the other parts of the laminated structure.

According to the present invention I use for this purpose an adhesive which consists of a solvent of high boiling point, i. e. 'at least 100 0., and preferably a polymerization product of vinyl acetate or an acrylic acid ester of the same basic material as the intermediate sheet but of low or medium viscosity which is compatible with the material of the intermediate layer. The adhesive contains no solvent having a lower boiling point than that above mentioned. The proportion of solvent of high boiling point is from to 75 per cent of the whole.

In putting the structure together I preferabl'y E apply this adhesive freely to both sides of the intermediate sheet, e. g. by immersing the 'latter ,1 in the adhesive mixture, though it may alter-4, natively or also be applied to the surface ofghe glass. The assembly of the component parts is that O performed at a temperature of between 60 30 these highly polymerized products.

90 C. under pressure, the adhesive being so composed as to be of syrupy consistency and also acting as a slip means i. e. the excess forced out under pressure serves to entrain and remove any air bubbles which may be present.

An adhesive of the character above-mentioned has been found to be highly suitable for cementing highly polymerised intermediate sheets i. e. layers in which polymerisation product of an acrylic acid ester or vinyl acetate has been carried approximately to the final stage, and which owing to the entire absence of solvents possess no powers of adhesion in themselves.

Attempts have been made to cement such highly polymerised intermediate layers to glass by means of adhesives containing a solvent of high boiling point and a solvent of low boiling point. Such adhesives can, however, be employed very thinly, and even then the low boiling point solvent has a tendency to diffuse into the intermediate layer and later to cause bubbles and fog. It has also been found that the joint formed by such thin layers does not possess sufficient elasticity, as the highly polymerised intermediate layers are extremely viscous in themselves and 50 performed at a temperature of to (ci.'49-s1) 6 tween the rigid sheet of glass and the highly viscous intermediate layer. If the known adhesives where employed for this purpose, together yvith a fatty liquid as slip means, it would be fogmd that this fattyliquid 10 would considerably reduce the cementing power hold splintered fragments. Owing the high of the adhesive and the capacity of ftihe' joint to viscosity of an intermtliategayer c r sisting of a highly molecular polymerisation product, the 1d fatty slip means heretofore proposed, would be unable to diffuse 111% the intermediate layer, but would be compelled, so far as it; is not again forced out, to mix with adhesive which would reduce the effectiveness of e ive.

A composite solvent may avefgi high boiling point per se but may also be incable for use n according to my present invention 1 t is a composite solvent lika diacetone alcohol which at a temperature of 80 to C. necessary for pressing the sheets of a laminated glass together, he-

- comes converted, in part, into lower boiling components. Such a substance is not a solvent of 8 high boiling point for thepurpose of my present invention. Acetone also is' not a solvent for The solvents of high boiling poir contained in the adhesive impart to the latter e property of. acting as slip means. The boiling point of the solvent should be situated as far as possible 35 above 100 C., and it is obvious that the higher the boiling point the smaller is the amount of this solvent which can diffuse into the intermediate layer, and gvith adhsives employed accord ing to this invention there will remain a sufii- 40 cient excess to act as slip means and to pick up and expel the finest particles of air from fi e joint.

With an adhesive according to my invention, the procedure for the production of laminated 45 glass and similar laminated products by means of highly molecular intermediate layers is that the adhesive is applied in excess amount to one component part of the structure (preferably to the interlayer), and the uniting operati then at such a pressure that the excess of adhesive is forced out of the jomt as slip means.

layer is caused to swell by immersion in the adheslve, and the connection then made at the Prefer- P ably, however, the highly molecular intermediate J above mentioned temperature, and at such a pressure that the excess of adhesive which remains adhering to the immersed plate or foil is pressed out of the joint as slip means.

The following examples illustrate my invention;

1. 50 parts by weight of a polyvinyl acetate of low viscosity are mixed with 50 parts by weight of ethylene glycol mono-methyl ether (B. P. 125 C.) at approximately 42 C. to form a homogeneous mixture. An adhesive liquid is thereby produced which is viscous, but permits of the immersion therein of the intermediate layer (consisting of highly polymerised vinyl acetate). The time of such immersion ordinarily amounts to approximately 30 minutes. The so treated intermediate layer is then removed, placed between two carefully cleaned sheets of glass, and united with thesheets of glass under pressure at a temperature of 60 to 90 C. The excess of adhesive which remains adhering to the intermediate layer acts as sluggishly flowing slip means.

2. 30 parts by weight of polyvinyl acetate of medium viscosity, and 20 parts of polyacrylic acid ethyl ester of low viscosity, are thoroughly mixed with 50 parts of the acetate of ethylene glycol mono-methyl ether (B. P. 144.5 C.) till a homogeneous mixture is obtained. It is advisable to perform this operation at approximately 50 C. The resulting viscous adhesive possesses extremely high cementing powers and is used to secure a layer of highly polymerised vinyl acetate between two glass sheets as described in Example 1.

By the expression laminated glass or the like" as used herein I mean bodies composed of sheets of glass with one or more intermediate strengthening layers, and also sheets of glass with a strengthening backing such as are used for refleeting signs.

By the expression highly polymerised vinyl acetate or an acrylic acid ester as used herein, I mean a polymerisation product which has a degree of polymerisation of between 600 and 680 (absolute viscosity 70 to 80). The polymerisation product of low viscosity has a degree of polymerisation of between 200 and 240 and the polymerisation product of medium viscosity" has a degree of polymerisation between 320 and 380 (see Staudinger "Die hochmolekularen organischen Verbindungen (1932) pp. 41 to 45). The medium viscosity polymerized product has an absolute viscosity of 30 to 40. These absolute viscosity figures are measured by the method given by Mayer & Mark, in Der Auibauder hochpolymeren organischen Naturstoff (1930) pages 1'75 to 1'77.

What I claim as new and desire to secure by Letters Patent is:

1. A laminated product including two sheets at least one of which is glass, and an interlayer sheet consisting of a polymer selected from the group consisting of polymerized vinyl acetate and polymerized acrylic acid ester, said polymer having a degree of polymerization between 600 and 680, an adhesive disposed between said first mentioned sheets and said interlayer sheet, said adhesive consisting of an organic solvent having a boiling point of not less than 100 C. and substantially free from solvents having boiling points below 100 C., and a polymerized unsaturated ester selected from the group consisting of vinyl acetate and. acrylic acid ester, which latter polymerized body has a degree of polymerization between 200 and 380, the solvent representing 35% to oi! the adhesive.

2. A laminated glass comprising two rigid sheets, at least one of which is glass, an interlayer of a resin which is a highly polymerized ester selected from the group consisting of vinyl acetate and acrylic acid ester, and having a degree of polymerization of between 600 and 680, and an adhesive between the first mentioned sheets and the said interlayer, said adhesive consisting of a polymerized ester selected from the group consisting of polymerized vinyl acetate and polymerized acrylic acid ester, and having a degree of polymerization between 200 and 380, and a high boiling organic solvent intimately mixed with said polymerized ester, said solvent having a boiling point above C.

ADOLF KAMP" FER. 

